Insulating confined spaces



c. c. HERITAGE 2,439,601

INSULATING CONFINED sPAoEs April 13, 194s.

zsneets-sneevz Filed March 2, 1943 Patented Apr. 13, 1948 l Weed Conversion aCom'pany, :SLJPaiL-Minmia corporationoffDelaware i l Application Marthe, 1943, senin No. 471352;

Cl'ais. (Cl. 2.021101) H l 1 i A :z` The'present invention relates to theiplaeernent been-feit4 "iiiitd Lil th'""ii`n'l'icial development of particles of thermal insulating material -t o 'f 'rfrige 'at'r `insliittlfr'r'l in -fpiallel `with the build up a thermally insulating integrated mass dvliliit'f tli'estic -alitiicial` 'reirig'erationl of such material in a confined space. AIn partici-1'u W'ith'ji histli's for vloilv heatlos's lar it relates to carryingthematerialin a gaseous i lou? cost e'filisiilati'g n'ate ilfand of insulatvehicle V(hereinafter referred "to `as air) toadeing fboeess ji'fpotat `as areluniformity in posited'growing mass of such particlesjformed each fjliintg-iahd ftiiifmity iroin cabinet lto by deposition of particles from the vehicle. calei'ltf iii ii'ulclli` :1in f- In its general aspect the invention con'te'niiii fproll'lemfofwpernia# plates completely conning'a space tobes`o`lld :10 nen, iii -Wliil sist fte settling'of ADaled with insulation material, ,whereby to -denne the bulk insulatiis'is lmpertt Su'eh resistform of the mass to `loe produced. The `'space maybe provided substantially completely, byor 0f "plililt Witli liethlakf ohagt con- Within existing articles. HoWeven'as `required or ducta'n il s'es; Ms Wiii. general .-r1ile, in the desired for the purposes of lthe invention, the T5 iange's-fniiterdiirilrfirates. `IhShe'lsp'aceto 'be llediis completely defined by-hound# fore. imprtafn U lr'iiriin'i nSitYfCOhSStently ingiiaoiel wells `having essentially some1-filtering with eeeptelilirsisteeftd sttliuglendlaccel'itarea for exhausting thegas'inwhich particles `of able insulittiiigoiztlue :Allthesflfatrs lead to a the insulating material are introduced, and liav- Ile'flosiwmili'is SUUJ'ECHO Crilr'Ol `for ingessentially inthe areaofthe'coniiningwlls, 4m, mtigl'hh. f i one or more inlet areas for'intro'ducingtlle gas ''i'fh `1`i`fi "-frfii iill fhS beei :no fIOWecoSt containing the particles, each Vsuch inlet 'area S'SS fiilkillg iSpeC-mterial.uniforlm being essentially in and a fraction of a confining 1y and integrally into a cabirietrimd iunifermly Wall o'r `facein a manner analo'gbustothe vrela- I'OII bhftwffbmetvn'a-PIUdUCOn-TlirielThe tion of the area of ap'ourin'g sprueinmoltls'for 25 pSlF-lveltiillrevides sucliunprDCSS, :and so casting instel articles to e; space-Genuine 'etree used it gives reproducible resultswitheny repreoflthemold, ucililetnateiilt-Vegetablebers such las Afrom Lltisalso argeherl aspect of theinventlonthat mya-rieadilyiloeprodliedifromstimeto .time

thepartieles of insulating ,material are' suonas' with reproducible propertiesivithiiilsivenispecimaybe consglidated ifma ga'ssltrng 'b'dy cation'sl,sandfwithssuchiiateiallzand lwiththe when in finally deposited form, `wherein in ooh'- Dleset iuvei11iiir1-ituiduit-distfliroeess` for uuidueting and completing .the introduction, :ses formly eueiemeieutlv inulletiue' Spades euch as enteringthe Space throughimt rea, may'ass thoseiirrefziigerators,:becomes availalble to the through `all or a part o'f the body as reguiredyto Il'rietmlii'ctueifslV 'sot refrigerators. :Reference is exhaustthroug'h filtering aree. g5 mede-ite my ieopendingteppiieetin Serial No. Another general aspect of the `invention per- 336.495;iiledfiMeywmZir-19210ivnow iPzatent No. mits the form of `the Space to be comme); or :2;3-25i055i11is`sued izluly:71943itdescribing reproangular, and not 1mm-,ed to paneLfO-rm Yspaces; du'ibleEberspwhiehsarefuseiul las particles "for Thus, the vehicular stream of 'gas is-lhtnidueeil leileetieoiitlieiireeutfmventien. at a. differential pressure, relative tothe *pressures i() Tfepresentfinvemm'sff cntnuatonnpaft atinlef, area and at l/ring-area,` andai; Suh of tiny prioi'ftappli'cationserial'No.'294;212,filed velocity that the particles suspended in the gas Septemerfuillsiwhereinlthe :principles .of the ere .terrieri with turbulence `inside the spese to pweesfureueleedfWhiehreplilieetienis generic all portions of the space remote --frornlnlet ere-et, tOitheT-preeeutieplilieatibnf t 'lhe present applica` andthat thedilerential pressure packs `the de- *45 tion iis a-eolpunieirttdf8era1 N0.' 477,751, and posite'd mess to e, consolidated body `fillingtlie SeiiM-Ndi'477i755'i1lae1iifled March 2', 1943,.es space `Wh`ile said pressure ofithe gas 'streanlis riliil diile'liilfisplent alllcaion maintained to and, if desired, even after' "the Sei-l N- z9`4'l212i "I-I'lifSe'rial No.l294;2121the 'incomplete filling of the space. M Veritiriibelrlg "ed is generic.totlleinventions Theinve'nti'o ig appncagble in mnyeldgjfor 50 lingf'flinie'liilisaidiSerilNor 4'77;751,in Serial examplein packing liber or' other insulatingflna- N-`477N55 d i-tlfpseritflllcti. The teral finto carboys to protect and insulate the invl-'itiibeirigilirdfinslid application Serial flasks of `liquid therein. However, its presently thiriifeiiiehe Vbeine preferred use is in insulating the'iloors'anil csbiy diiiiieition-ad in serial nets of refrigeratrs, such as are used in lils. '4' l1 'ntllljilg=llilned in the "In the field `of `artificial refrigeration, :high '-gnei tothenvention standards for insulation in ooinestie -en-zl'other bijrg'ftieiinediin' uniud/471755: refrigerators have developed `in order4 tonnin'i- Itisxfrlijett- "t rselitinventionf-toell lnizeheat loss, because highheat lossJadds tothe aispgeo n part yboidingfacialwalls cost of operation. `conside'reisledlnieulty v4lists '60 nrovl'dlrig"an-oneningpsueh esithe space in en t afiaaei 3 open-topped box containing a body and providing an opening through which the body may or may not project, and conned in remaining-part by closure means for said opening, saidv closure having inlet area for introducing a stream of gas containing suspended particles of insulating material, and having also filtering area for exhausting said gas.

It is a particular object ,of the invention to provide such a confined space that Vit may have a region thereof remote from an inlet area, with obstructingvwall area in the direct line between said region and said inlet area, whereby'insulating particles are carried around the said obstruction in filling the space. f.

It is a particular objectlof the invention to fill the space providedfor Ainsulation in refrigerator cabinets in which a food-compartment is already mounted, by employing a fixture closure for open area lying between the cabinet and compartment in the vicinity of the door opening which gives access to the food compartment through the cabinet, said closure havinginlet area for introducinga stream of gas containing insulating particles, and having also filteringarea for exhausting said gas in filling the insulating space.

Various other and ancillary objects and advantages of the invention will become apparent from the following description and explanation of the invention which is given in connection with the accompanying drawings in which: c

Fig. 1 represents blowing apparatuses vit may be employed to :lill a box-like container;

Fig. 2i is a vertical cross-section in a perspective view of a carboy containing a bottle spaced from the walls ofthe .carboy, the carboy being fitted with a substitutecover as a fixture for the present invention; l

Fig. 3 is aperspective yiewofithefixture;

Fig. 4 is a vertical cross-section of the completed packed carboy; 5 y 1 Fig. 5 is a plan view. of a refrigerator minus its door with the refrigerator cabinet-,lying hori- Zontally on its back;

Fig. 6 represents afixture to be placed over the cabinet shown in 5 when the breaker strip of said cabinet is not yet in place; vand Fig. 7 illustrates in. plan VView the cabinet Yof Fig. 5 with the fixture of Fig. 6 in place thereon.

In my earlier parent application Serialv No. 294,212, the process is described generically and specifically withrespect toV various forms .of the space to be filled, and various types of spaceconfining walls, .and removable fixtures, having particular reference to variations'in` the process for insulating domestic-type refrigerators. These variations include filling a refrigerator in which therfood compartment is already mounted, and also Vin which the food compartment is not mounted. In the latter case, a fixture inthe form of a dummy for the food compartment is employed, and the fixture is used to provide filtering area, and may be used to provide inlet area. The process is iiexible for accommodating it to various types of refrigerators, as well as various types ofV spacesnot necessarily those of refrigerators. In the said .earlier vapplication there is claimed specifically a method of filling a refrigerator in whichthe food compartmentV is mounted, both the cabinet and therfood compartment having openings therein for accommodating the insertion into the food compartment of a vrefrigerating unit. One of thesaid openings tothe space is used for introducing the gas, while the other is blocked off. The open space at the doof` theV space.

opening between the cabinet and the food compartment, where breaker-strip material is located in the completed refrigerator, is closed by a fixture or closure provided with filtering area, and preferably including also some ifnperforate area. Thus, the gas introduced passes through the gas filtering body of insulating material built up in Then the fixture is removed, and breaker'strip used to close the gap. The space between the openings for 'the unit thus has insulation, which may be disturbed as necessary in making connections when installing the refrigerating unit. Y

It is also set forth that the stream is introduced at a differential'pressure between inlet and filter areas. This may be effected by having atmospheric pressure at either the inlet' area, or at the filtering area. The latter is preferred for many practical and mechanical reasons.

In the present application it is likewise intended that the pressure be a differential one, :but to simplify the description andthe illustration, only the preferred one of super-atmospheric pressure at inlet area is'specically described and illustrated Without intention Vto limit the invention thereto. Y L

After the introduction of the insulating material into the spaceto be insulated, especially in a refrigerator, there are numerous mechanical operationsVA which may be necessary to complete the article for use or sale. However, these form no essential'part of the invention, and detailed description and illustration of them areherein omitted.

The preferred closures or other means having filtering area are l'preferably permanent Vfixtures used in a production line, and are in preferred practice removed after each use. However, Athese may be of other structure, for example, metal or Vcloth filters of such character that they need not be removed.' When retained, they may be a permanent part of the -final structure, covered or not. Hence, the Vremoval ofsuch closures is not y'considered an essential part of the process'. But in certain cases it may be included as an essential part of certain aspects orvariations of the invention. g

The present invention may be used for fibers, flakes and particles of other forms. Examples of fibers are hair, AWood fiber, vegetable fiber, kapok, mineral Wool, glass wool, asbestos, straw, grasses and many others. Examples of other materials are flaked paper, exfoliated vermiculite, mica, ground cork and like materials. Fibers are preferred, because they mat and felt and produce stable vforms in more complex variations of the invention where fixtures maybe used and removed. The following illustrations are, therefore, given with respect to Wood fiber, such as that according to my said copending application Serial No. 336,495, filed May`22, 1940, now Patent No. 2,325,055, issued July 7, 1943, which were developed primarily for use in the present invention.

The invention involves the building up of a consolidated gas-filtering body of particles of insulating material introduced as suspended matter in a stream of gas, into a conned space to be insulated; and it involves the provision` in the confining walls of said space of filtering area to retain the particles and exhaust the gas. The location of inlet area, the number of inlet areas, and the location, sizeand number of filtering areas are not critical With respect to any given space. l This is because the stream of gas is in.-

bulence the particles may deposit in regionsl` some oi" which are adjacent to filtering area,4 and others of` which are remote fromV both inlet area and, ltering area.` The resulting deposit grows' toward the inl'etlarea,` and to orA through the inlet area. In such case,` the filtering area closeto or adjacent inletareafacilitates the deposition of, the last deposited material. Theconditions establish a complexity cf air currents which change as` the remaining space to be iilled changes. Cyclonic currents have been observed which tend to throw carried particles centrifugally out"` of the localA stream, and deposit them by' centrifugal force and inr the manner described. Also direct deposition by filtration has beeny observed as oneV ofthe resul-ting actionsto deposit the introduced particles.

The preferred means for creating the moving stream of gas carrying suspended particles is illustrated in Fig. 1. A fan-type blower 45 has pilpe- 4-6f`for" the entry of airintowhich. ber may be fedby hand, or by a mechanical device, such as a picker, 4or a worinA screw 46a- The fan dischargesA downwardly through conduit Y43"?, to which suitableconnection is made.

`(f'fmsider the apparatus ot Fig. 1 when the pipe 41 is 6 inches in 'diameter' and connected `to a spaeeftobe filled. The fan is operated at 3740 R-.`P. M1 by a 125 H. P; motor `of 1800l R. P, lVi. Running idle (connectedand operated but no lfbenied), the measured pressures are as follows? Table I Pressure in inches In p1pe 41 ,Water Iiateral'tatic) pressures.; 8.5. TOtsLpreSSure... i ,10.25. .l z Velocitypressure 1.75.` Velocity/.L 5300'ft. perminute. Output 1040 cu. ft. perminute.

The. system shown in 1 has been used to fillia certain space 1A; full, then again to 1/2 full, then: to V4 full, and thento-100% full, with measurementsot the)` system (idle)` at each stage. The measured values are combined: in Table II with valuestaken from Table I and are in thesame units as' those in Table; I.

Itisnotedithatunder conditions where the exit llfljis open. `Amoinenturn isestablished into pipe 4T. As this is blocked olf, the movingl streamjs retarded, at first in part, and ber gradually lls up the inleteonduits. 'A window (later described) indicates this and the process maybe stopped. IfAvnot stopped' the back pressure at the inlet blows liber back inpipelfd. Thus, fiber fed into the inlet will also be blown out the inlet. The ap.- pearance of back-feed or back-pressure is airindication of the final status of being filled.

Many factors influence the result, andpractically, it necessary to arrive at standard conditions for the particular equipment used, and the job at hand. For exampleit has been found to be a general rule, that. the faster the fiber is fed, the less the density of the mat obtained.

However, this ruleis limited to a very short period of time. In one tested instance, the feeding time for the space was. varied from fractions of' a minute to several minutes.` The curve of density has been plotted vertically against feeding time plotted horizontally, The curve rises rapidly, and at about 25 seconds it begins to flattenout. In about seconds it has reached a maximum density. Such curves were obtained with different fan speeds, and it was found that high speeds (greater kinetic energy to liber) at the same feeding time gave higher density mats., By constructing such curves from experimental procedure,4 the conditions for most efi'icient operation .and for uniform operation may be easily determined.'

The space to be lled need not be of boxlike or panel-like form. It may be more complex, and even be what is called angular that is, it has one ormore regions between which and at least one inlet areato the confined space there lis no connectingstraight line lying wholly within the confined` space, but rather there is at least one obstructing space-confiningwall. This compels particlesto iiowto such a region by an indirect line, such as an anglilar" line, the paths, however, being complexbecause` of the turbulence within the space. The velocity of the streamof gas introducedand the location and sizeof filtering area relative to inlet area are all such that particles are carried with "turbulence to allfpor` tions of the confined space.

Fig. 2 represents a carboy, such asiemployedfor shipping acids, on a platform 5 8; there being a screen opening 59 in the bottom to retain particles, and to serve as filtering area when not obstructed (as shown) `by platform 53. The carboy has a casing 60 of box-like form in the bottom of which,-as at the corners, are spaced blocks 6l of spacing material, such as; of cork or composition, or wood, but preferably of insulatingmaterial such as insulating fiber board. Blocks 6l space a bottle or flask E2 abovev the bottom B3 of the casing, providing space 64beneath the` bottle,

iswholly or toa degree blocked, as when the space isful1', there is afback pressure encountered at the inlet to the centrifugaljfan.

The back-pressure is animportant feature of the use, of super-atmospheric, pressure feed, with apparatusperrnitting back pressure. Consider in Fig. 1` that the fan may ru'n while the feed line land they also space the bottle fromV the sides E5 of the casing, thus providing a circuitous peripheral space 66. Usually the mouth 61` of such a bottle projects froma closed casing, as through ahole 68 in` a cover 69, undera protectingbridge 1 In accordance with the present invention. before such a cover 6.9. is applied. aAV temporary clo-V sure or fixture plate (Fig` 3) is fitted over the casing. As shown, this fixture has a body plate 'I l, a flange 12 to t over the casing.,A and a hole 13` is provided with means to seal the hole to the neck of the bottle, such as an elastic sheet rubber ring 14. Area l5` in plate 'H represents inlet. area, and it is covered by ahood- 416 connectedto or attachable to a conduit 11. Conduit 'l1 may be connected to the mower' of Fig. s. A altering area is provided in plate 1| by mounting therein wire screen 19.

Upon blowing 'air containing insulating particles, such as fiber, into` casing 60'by means of the xture in place over the casing,` the fibers pack under and around the bottle and to thexture, and to or into the hoodv 16. The rfixture is then removed, and the cover (of Fig. 4) is secured in place.

As applied to refrigerator cabinets, the present invention is best employed with cabinets in which the food compartment isv already mounted.` Fig. 5 represents such, in plan View with a conventional cabinet 80 lying on its back. The cabinet has a door opening facing upwards. The cabinet shell, when of metal, has a peripheral internal flange 8|, across the corners vof which braces 82 are secured. A food compartment 83 i-s mounted inside the cabinet by means of an external flange 84 thereon, secured to said braces 82. This forms a space 85 around the food compartment, and under it (in the position shown) to receive insulation. In the back of the food compartment is illustrated a temporary plate 86 covering an opening for use in connection with a refrigerating unit later to be installed. The plate 85 aids in confining the space to be insulated, and if desired a screen 86a with an adjustable slide cover 86h may be located therein, for non-use of its filter-V ing area, or for adjustment in area for use as ltering area. This is representative of any other filtering area, not in the fixture, which may be used. In preferred practice screen 86a'is covered.

bottom front of the operating refrigerator, behind which operating machinery may be located.

'I'he peripheral open space 85 at the door opening is covered by a temporary closure, or fixture, shown in Figs. 6 and 7. The closure comprises frame members 90 fitting over flange 84, and frame members 9| tting overy flange 8l, with space .between the frames. At the corners, this space may be rendered imperforate, by mean-s 92 providing imperforate area inV part confining space 85. Adjacent the said 'corner means 92 are screens 93 providing filtering area in part confining said space 85. Between the pairs of screens 93 on each panel side f the space 85, there is inlet area defined by the open ends of covering hoods'94 to 91, which are connected by conduits 93 to a common unit 99 into which the air stream is blown. Hoods 94 and 95 may be bifurcated internally as shown. Windows H19 permit seeing when fiber or the like packs into the hoods, indieating completion of the filling of space 85.

The fixture is then removed, and the breaker strip 81 is substituted therefor-over the body of insulating material exposed on removing the fixture.

Wood fiber may be packed into the space at various densities, as from 2.0 to 4;5 pounds per cu. ft. to provide a mat'resistant to settling by shock, the mat in suchrange having a K-value in the range from .20 to .27.` However, itisto be the K-value out of this range. The packing by arresting moving fibers provides a. highl degree of felting, which is a factor indicating resistance to settling. Y

The usevof a fan is preferred for the reason that it is a means of unfelting the fibers to substantially individual bers. It is this form which gives the best results. However, broadly, the fibers need not be completely unfelted, and may be in clusters or small aggregates. Use of other means, such as vacuum onA the screen end, or feeding fiber directly into a current of air, is conducive to providing such loose aggregates, rather than individual particles of fiber. The important point is that these are not under mechanical pressure to felt them, and they tend tounfelt in process. y

The terms screening means? and "filtering area as used herein or in the claims refer toan area with any effective lattice or perforatedv member which acts as a screen to filter particles from the carrying gas, and it is to be distinguished from a member porous to air and fromya crack or an elongated slot. 7 f

Numerous modifications and uses of the invention are contemplated in the appended claims.

1. In depositing particles of insulating material into the space defined and confined by walls ,including the walls of a refrigerator cabinet and of a food compartment mountedr therein, and including removable closure means over said space at the door opening of the refrigerator, said closure means having a plurality of introductory inlets opening into said space including one to each panel-form space at the door opening,

of which walls the space conningsurfaces in clude a major portion which is substantially-,resistant to the passage of gas and one or more remaining portions, each in the form of screening means with foramina relatively minute compared with said one or more inlets, for venting gas from said space and for retaining said particles in the space, the method which comprises, suspending in a moving gas; particles of insulating'material which pack to a consolidated Abody that is a gasiiltering body at an insulating density of the sopacked particles; introducing the resulting moving gaseous suspension into said space by conducting the suspension to,` and through said `introductory inletsysimultaneously venting said tion and packing of particles in margins oftheY turbulent space; continuing said introduction, said maintenance of turbulence, and said venting of said gas through said screening means, and also through said growing mass at least until a body of said particles beginstoI form in each ofV said inlets and said spaceis completely packed with said particles consolidated to a gas-,filtering body at anI insulatingdensity andfresultingly molded into said space andcompressedtherein by thediierential introductionpressure between'.

.said closure means having a .pluralityf-o 2. In depositingzparneies cf :insulating material into the space dened ,and confined byl-,walls including the walls of a refrigerator cabinet-and of a yfood compartment Vm unted therein, and

Iincludi'ng removable closure .means over saidf,

space at 'the door opening of the refrigerator,

`iilcttiily 'inlets opening into -Space 1 `one to each panel-form spacetat lathe dem' Vo iin-g, of which walls thelspaeconning ,surfaces include a maior portion which uis substantially resistant to the passage of gas and one or more remaining portions, each in the form of screening means with foramina relatively minute compared with said one or more inlets, for venting gas from said space and for retaining said particles in the i space, of which screening means at least one is in said closure, the method which comprises, suspending in a moving gas, particles of insulating material which pack to a consolidated body that is a gas-iiltering body at an insulating density of the so-paoked particles; introducing the resulting moving gaseous suspension into said space by a conducting the suspension to and through said introductory inlets; simultaneously venting said gas from said space through said screening means, and there filtering said vented gas from particles, thereby depositing and packing particles to form a growing gas-filtering mass thereof in corresponding portions of said space over and extending away from said screening means; simultaneously maintaining in the remaining portion of said space a condition of turbulence of said gaseous particle-suspension by maintaining a high and sufficient velocity therefor in introducing said suspension whereby the turbulence causes deposition and packing of particles in margins of the turbulent space; continuing said introduction, said maintenance of turbulence, and said venting of said gas through said screening means and also through said growing mass at least until a body of said particles begins to form in each of said inlets and said space is completely packed with said particles consolidated to a gas-filtering body at an insulating density and resultingly molded into said space and compressed therein by the diiierential introduction pressure between said inlets and said screening means; removing said closure means and retaining in situ the material packed into said space; and applying a confining material over the open space left by removal of said closure means.

3. In depositing particles of insulating material into the space defined and coniined by walls including the Walls of a refrigerator cabinet and of a food compartment mounted therein, and including removable closure means over said space at the door opening of the refrigerator, said closure means having a plurality of introductory inlets opening into said'space including one to each panel-form space at the door opening, of which walls the space conning surfaces include a major portion which is substantially resistant to the passage of gas and one or more remaining 'portions located in said closure means, each in the form of screening means with foramina relatively minute compared with said one or more inlets, for venting gas from said space and for retaining said particles in the space, the method which comprises, suspending in a moving gas,

partlclesof insulatingmaterial which pack to a consolidated at` is ya .gas-:filtering body at an sulat'ing density ot the so-packed particles;

"introdcingfthe resulting moi/ing` gaseous sus- `simultaneouslyi/renting said .gas from 'said space through said fscreening `jineans, 'and there filtering rticles, "thereby depositf s 'toform ja growing` gas- K stli'ereof in corresponding portions space over ande `ding [away from said screening Jnears; simultaneously maintaining in the remaining portion of said space a condition or turbulence of said gaseous particle-suspension b'y maintaining a Ahigh and suiiicient velocity therefor in introducing said suspension whereby the turbulence causes deposition and packing of particles in margins of the turbulent space; continuing said introduction, said maintenance Vof turbulence, and said venting of said gas through said screening means and also through said growing mass at least until a body of said particles begins to form in each of said inlets and said space is completely packed with said particles consolidated to a gas-filtering body at an insulating density and resultingly molded into said space and compressed therein by the differential introduction pressure between said inlets and said screening means; removing said closure means and retaining in situ the material packed into said space; and applying a conning material over the open space left by removal of said closure means.

4. In depositing particles of insulating material into the space defined and conned by walls including the rectangularV Walls of a refrigerator cabinet and of a rectangular food compartment mounted therein and including a removable closure over a rectangular space peripheral to the food compartment at the door opening of the refrigerator, said lclosure having four spaced introductory inlets opening into said peripheral space, of Which walls the space confining surfaces 'include a major portion which is substantially resistant to the passage of gas and one or more remaining portions, each in the form of screening means With foramina relatively minute compared with said four inlets, for venting gas from said space and for retaining said particles in the space, including screening means in said closure, the method which comprises, suspending in a moving gas particles of insulating material which pack to a consolidated body that is a gas-filtering body at an insulating density of the so-packed particles; introducing the resulting moving gaseous suspension into said space by conducting the suspension to .and through said four introductory inlets; simultaneously venting said gas from said space through said screening means, and there filtering said vented gas from particles, thereby depositing and packing particles to form a growing gas-liltering mass thereof in corresponding portions of said space over and extending away from said screening means; simultaneously maintaining in the remaining portion of said space a condition of turbulence of said gaseous particle-suspension by maintaining a high and suiiicient velocity therefor in introducing said suspension whereby the turbulence causes deposition and packing of particles in margins of the turbulent space; con` said screening means and also through said grow-v ing gmassat least until a body of saidparticles begins to form Vin each of said four inlets and said space is completely packed with said parti- 1 cles consolidated to a gas-ltering body at an insulating density and resultingly molded into said space and compressed therein by the differential introduction pressure between said inlets and said screening means; removing said closure.

and retaining in situ the material packed into said space; andapplying a confining material over the peripheral space left by removal of said closure.

CLARK C. HERITAGE.

le of this patent:

REFERENCES CITED Y lThe following references are of record in th UNITED STATES PATENTS Ericson et al. May 14, 1940 

